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Biomedical subjects

G V Alm

Publications and source records attributed to G V Alm.

At least 73 records · Page 4Linked to original sources
PubMed1982

Lectins as inducers of interferon-gamma production in human lymphocytes: lentil lectin is highly efficient.

Several of many tested plant lectins induced interferon (IFN) production in cultures of human peripheral blood mononuclear leucocytes (PBL). The mannose-binding lectin obtained from Lens culinaris (LCL) was a particularly efficient inducer of trypsin-sensitive antiviral activity, which qualified as IFN-gamma because it was 90-95% destroyed by pH 2 treatment but not neutralized by anti-IFN-gamma antibodies. However, such antibodies neutralized the residual 5-10% pH 2-resistant IFN, which therefore represented IFN-alpha. Further evidence for the IFN-gamma nature of the LCL-induced IFN was that its production in PBL cultures required both T lymphocytes and macrophages and that its induction of antiviral resistance in human amnion cells was significantly delayed compared with IFN-alpha. Under optimal conditions LCL induced titres of IFN-gamma corresponding to more than 20,000 IFN-alpha units/ml medium, higher than observed with other tested, established IFN-gamma inducers. Other desirable properties of this lectin, as discussed, also suggest that it will be of value for efficient large-scale IFN-gamma production.

Humans↗
PubMed1981

Positive correlation between degree of parasitemia, interferon titers, and natural killer cell activity in Plasmodium falciparum-infected children.

Natural killer (NK) cell activity and interferon levels have been measured in the peripheral blood of children acutely ill with Plasmodium falciparum infection. The NK cell levels were found to be raised in the malaria-infected children, with a positive correlation between the degree of parasitemia and lytic activity. Comparatively high titers of antiviral activity was discovered in sera from the majority of P. falciparum-infected children, again positively correlating with the degree of parasitemia and NK levels. The characteristics of the antiviral factor indicated alpha-type interferon to be the dominating agent involved. Addition of exogenous interferon in vitro potentiated the NK levels of PBL from normal children while having no significant impact on cells from malaria-infected children.

Antibodies, Viral↗
PubMed1980

Lymphoma development from transplanted murine leukemia virus infected organ cultured thymuses: inhibitory effect of in vitro interferon treatment.

Thymuses of 14-day-old AKR mouse embryos were infected with Gross murine leukemia virus (MuLV) and then maintained in organ culture for 3 weeks. When they were transplanted to 3-week-old (AKR X C3H)F1 mice, approximately 50% of these developed T lymphomas within 3-4 months. Most (22/23) tumors were of host, F1-hybrid, origin while only one was of donor AKR type. No clear evidence for in vitro MuLV-induced lymphoma cells was therefore obtained. Exposure of MuLV-infected embryonic thymuses to interferon during the organ culture period significantly reduced the incidence of lymphomas in mice receiving such thymus transpalnts. Interferon also prevented the appearance of detectable numbers of MuLV antigen-containing lymphocytes in infected organ-cultured thymuses. In contrast, despite the use of very high interferon concentrations, no effects were seen on the number of viable thymic lymphocytes, their proliferation or responsiveness to the polyclonal T-cell mitogens concanavalin A (Con A) and leukoagglutinin (LA). Thus interferon, presumably through an antiviral effect, can limit the MuLV infection in the thymus and its consequence, i.e. development of a lymphoma.

AKR murine leukemia virus↗
PubMed1978

Role of the thymus in generation of lymphocyte functions. III. Further studies of the alloreactivity of lymphocytes developing in mouse thymus organ cultures.

Thymuses of 14-day-old mouse embryos could be maintained in organ culture, using serum-free medium, with generation of lymphocytes that showed strong proliferative reactivity to allogeneic spleen cells in mixed lymphocyte cultures (MLC). Such organ culture derived thymocytes also developed cytotoxic activity against target cells carrying the alloantigens of the stimulating spleen cells in the MLC. The generated cytotoxic activity was, however, proportionately lower than that seen with thymocytes of young mice. A time course study showed that cells with apparent reactivity to both allogeneic spleen cells and to the mitogen Concanavalin A (Con A) first appeared in the thymus organ cultures on day 8-9.

Animals↗
PubMed1977

Spontaneous and induced appearance of murine leukemia virus antigen containing cells in organ cultures of embryonic mouse thymus.

The potential of embryonic thymus organ cultures for studies on relations of endogenous MuLV, lymphoid cells and thymic microenvironment to lymphoma development were evaluated. Four main findings are reported. First, thymuses of 14-day-old CBA and AKR embryos could be maintained in organ cultures for at least 9 weeks with sustained production of lymphocytes. Lymphopoiesis in CBA and AKR thymuses were not grossly different. Secondly, an indirect immunofluorescence (IF) technique demonstrated spontaneous appearance of MuLV-antigen-containing cells in AKR, but not in CBA thymuses. Such spontaneous MuLV expression first occurred after 16 days of organ culture, thereafter infrequently and at random in individual thymus cultures. Thirdly, incubation of AKR and CBA thymuses in lymphoma extract containing AKR-type MuLV at initiation of organ cultures induced MuLV-antigen-containing cells. These were first detected after 7-14 days in culture, somewhat earlier and initially more frequently in AKR than in CBA thymuses. In the former, induction was accompanied by a clear reduction in the number of lymphocytes per thymus. Fourthly, iododeoxyuridine (IdUrd) treatment of AKR thymuses on cultute day 0, 3 or 7 decreased the number of lymphocytes per thymus and induced appearance of MuLV-antigen containing cells, assayed 8-20 days later. The IdUrd effect was most marked on day 0, and decreased sucessively on days 3 and 7. IdUrd had a much slighter effect on CBA thymuses, causing a lower reduction in cell numbers and inducing few MuLV-antigen cells. These main results clearly demonstrate the potential usefulness of the organ culture system for studied on leukemogenesis. It may be directly applied to answer several questions raised by detailed findings in our study.

Animals↗
PubMed1977

Natural cell-mediated immunity to lymphoma cells. I. Characteristics of effector cells in a cytostasis assay in vitro.

Spleen cells from normal, nonimmune, CBA or (CBA X AKR)F1 mice markedly and rapidly inhibited the incorporation of [3H]thymidine by two different T-cell lymphomas in an in vitro cytostasis assay. These were the I-529 lymphoma of spontaneous AKR origin and the Moloney murine leukemia virus-induced YAC lymphoma of A mouse origin. Spleen cells were the most efficient inhibitors for both types of target cells, whereas lymph node cells were much less active and thymus cells showed little or no activity. Granulocytes, as well as conventional T- and B-lymphocytes, were excluded as important contributors to the cytostatic cell population. Spleen cells were separated on nylon wool, Sephadex G-10 columns, or plastic petri dishes and tested for activity in the cytostasis assay or for cytotoxicity against 51Cr-labeled lymphoma target cells. Adherent cells carried almost all cytostatic activity against the AKR lymphoma but also showed significant cytotoxic activity against these target cells. In addition, the cytostatic activity against the YAC lymphoma was mainly due to adherent spleen cells, but nonadherent cells were relatively more active against this target than against I-529 cells. Such nonadherent spleen cells further showed increased cytotoxic activity, compared to the whole spleen cell population.

Animals↗
PubMed1977

In vitro establishment and some properties of AKR thymoma cell lines.

Lymphoid cell lines could easily be directly established in vitro from spontaneous thymomas of aged AKR mice. The established lines all carried the Thy-1.1 antigenic marker of T lymphocytes. They differed markedly, however, from one another in several respects. Thus, they showed high or low quantity of Thy-1.1 antigens per cell, high or low sensitivity to cortisone and thymidine, as well as differing morphology and growth rate. The observed heterogeneity suggests that such AKR thymoma cell lines may provide a valuable tool to study T lymphocyte properties and the biology of the AKR thymoma, in particular non-immune and immune mechanisms influencing thymoma cell growth.

Animals↗
PubMed1976

Morphologic and antigenic maturation of lymphocytes in the mouse thymus in vitro.

A simple technique for organ culture of the thymus of 14-day-old mouse embryos is decribed. It allowed a characteristic time-dependent development of the immature thymus into a lymphoid thymus with large numbers of nondividing small lymphocytes. Most of these cells carried the T-lymphocyte antigenic markers Thy-1 and TL, and all expressed H-2 antigens as determined in cytotoxicity assays. They probably developed from precursor cells without detectable Thy-1 and TL. This development appeared to be dependent on the thymic microenvironment, since it also occurred in serum-free organ cultures and in cultures with medium supplemented with serum from nude mice.

Animals↗
PubMed1976

Role of the thymus in generation of lymphocyte functions. I. Demonstration of lymphocytes reactive to mitogens and allogeneic cells in the embryonic mouse thymus in organ culture.

The thymuses of 14-day-old CBA mouse embryos cultured for 14 days in organ cultures supplemented with mouse serum contained lymphocytes that were highly reactive to the mitogens concanavalin A (Con A) and leukoagglutinin (LA) and to irradiated allogeneic spleen cells in vitro. In contrast, thymocytes derived from fetal-calf-serum-supplemented organ cultures displayed much weaker responses to the two mitogens and little or no response to the allogeneic spleen cells. Control thymocytes obtained from 1-month-old CBA mice responded well to Con A but not to LA. The responses of these cells to allogeneic spleen cells were delayed compared with the organ-culture-derived cells, which responded promptly, with a maximum already on culture day 2-3. The results demonstrate that the organ culture system provides a convenient model for further study of the generation of immunoreactive cells in the mouse thymus.

Animals↗
PubMed1975

Analysis of time dependent changes of lymphopoietic activity in organ cultures of embryonic chicken thymus.

The time dependent development of lymphocytes in organ cultures of the thymus obtained from 10-day-old chick embryos was characterized by an initial phase of exponential increase of the number of lymphocytes per thymus followed by a plateau phase with no further increase in cell number. The proportion of cells in DNA synthesis dropped rapidly during the first 10 days of culture. Simultaneously the lymphocytes turned progressively smaller, as evidenced by both cell diameter and dry mass and constituted a homogeneous population of small cells at the end of the culture period. Thymic anlagen partially depleted of lymphoid precursor cells by a short hot pulse with 3H-TdR showed a prolonged exponential phase and reached normal plateau cell numbers 2-4 days later than usual. Furthermore, at least in the first part of the plateau phase, a reduction in the number of lymphoid cells per thymus resulted in a recovery in terms of the cell number which was associateed with increased DNA synthesis. These results are compatible with the regulation of thymic lymphopoiesis in organ culture through a mechanism operating via cell density.

Animals↗
PubMed1975

Ontogeny of spontaneous rosette-forming cells in the chicken. With special reference to the bursa of Fabricius.

Cells forming rosettes (RFC) with sheep erythrocytes (SRBC) and rabbit erythrocytes (RRBC) were studied during the ontogeny of the bursa of Fabricius of the chicken. The frequency of SRBC-RFC was low but significant in the bursa of 15-day-old embryos, and increased therafter in an approximately linear fashion with the age of the bursa donor until at least in 43-day-old chickens. The total number of SRBC-RFC per bursa increased throughout the ontogeny with no evidence for any abrupt increase after hatch. The mean number of SRBC bound per RFC also increased after hatch. In contrast the frequency of bursal RRBC-RFC was high in 15-day-old embryos, significantly decreased on embryonic day 18, remained low until at least 7 days after hatch and then increased significantly. The total number of RRBC-RFC per bursa in contrast remained relatively constant during the embryonic period and the first week after hatch and thereafter increased markedly. No change in the mean number of RRBC bound per RFC could be demonstrated during the ontogeny. RRBC-RFC were also frequent in the yolk sac, spleen, and thymus of 15-day-old embryos.

Age Factors↗
PubMed1975

Effects of mitogens for mouse B lymphocytes on chicken lymphoid cells.

Lipopolysaccharide from E. coli (LPS) and purified protein derivative from tuberculin (PPD) increased the [3H]thymidine incorporation of chicken spleen cells in culture. No such stimulation was observed with dextran sulphate. Thymus and bursa lymphocytes were not stimulated by any of these compounds. Spleen cells from chickens chemically bursectomized with cyclophosphamide treatment showed decreased responses to LPS and PPD, but responded normally to the T-cell mitogen concanavalin A. None of the tested mitogens induced polyclonal antibody synthesis or directly enhanced the primary antibody response to sheep erythrocytes (SRBC) in spleen cell cultures. LPS-coated SRBC, however, enhanced the in vitro antibody response to SRBC. The results suggest a moderate proliferative response of chicken lymphocytes to LPS and PPD, possibly involving B cells, but not further effects comparable to those on mouse B lymphocytes.

Animals↗